A radiation medical image diagnostic apparatus such as an X-ray diagnostic apparatus is an apparatus which provides medical information of an object based by an image based on the intensity of X-rays having passed through the object. The radiation medical image diagnostic apparatus plays an important role in medical practice including diagnosis and treatment. When imaging an object using an X-ray diagnostic apparatus, the object needs to be imaged from various angles in order to obtain effective information from the object. To do this, for example, the X-ray diagnostic apparatus has an auto-positioning function of registering in advance the position and angle of a C-arm which holds an X-ray tube and an X-ray detector, and moving the C-arm and a top to the registered positions by a simple input operation (input from a preset button).
However, to execute the auto-positioning function, the position of the C-arm and that of the top need to be associated with each other. For example, in a system in which a portable C-arm or top having wheels is combined, the position of the top and that of the C-arm are not associated with each other, so the above-mentioned auto-positioning function cannot be executed. The user needs to move the C-arm and the top by a manual operation, and a long time is taken to move the C-arm and the top.